Design and Development of Nonlinear Predistorter using Hybrid Memory Envelope Polynomial for Radio over Fiber (RoF) Applications
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Date
2016
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MPUAT, Udaipur
Abstract
Before the crisis that affected the telecommunications at the beginning of the millennium, the major telecommunication operators invested a considerable amount of capitals to install optical cables around all over the world. In fact they foresaw of future, for the customers all over the world. One of the advanced technologies in optical fiber communication systems that support efficient convergence of wireless and optical access network structure is Radio over Fiber (RoF). In RoF, light is modulated by using a radio signal and sent over an optical fiber link to simplify wireless access. The demand for high-speed wireless communications is increasing rapidly. One major problem that may be encountered in these RoF links are nonlinear distortions experienced in the various cost-efficient devices mainly due the E/O conversion of devices. Various compensation techniques are suggested and investigated such as digital signal processing, feedback, feedforward and predistortion technique to reduce nonlinear distortion for RoF link. The predistortion is one of most suitable technique to reduce the nonlinear distortion for RoF link .Several behavioral models of predistorter have been proposed to model and linearize the RoF system. Extra closeness and accuracy in performance can be acquired when utilizing a memory polynomial to evaluate nonlinear practices than utilizing memory less polynomial as a part of RoF transmission. Those behavioral models are Volterra model, Wiener model, Parallel-Wiener model, Wiener-Hammerstein model, MPM, EMPM model etc.
In this thesis a new hybrid envelope memory polynomial (HEMPM) based predistorter is proposed for RoF applications. The predistorter has been designed after in-depth analysis of the mathematical equations meant for performance determination of RoF link. After implementation of the process flow chart it is concluded that the designed predistorter is capable of achieving very good compensating ability as compared to MPM and EMPM predistorter model. Modeling and testing of the proposed predistorter has been performed on the OptiSystem V.13 & MATLAB R2013a and sub-sequentially obtained results prove its superiority over conventional predistorter The results reported in the thesis reveal that the developed predistorter achieves minimum ACPR of 5.8 dBm, NMSE of -4.48 dBm and EVM of 1.95 % with memory length Q=3 and nonlinearity order K=7 at minimum power of -4dBm which gives excellent performance among the developed system so far and satisfies the requirements of long distance and high speed communication very efficiently.
Description
Design and Development of Nonlinear Predistorter using Hybrid Memory Envelope Polynomial for Radio over Fiber (RoF) Applications
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Citation
Vyas and Agrwal, 2016